As an example of a ceramic base, a DBC ceramic substrate bonding a metal foil, such as a copper foil, thereon to be unified is generally used. The DBC ceramic substrate used in a semiconductor power module is advantageous not only in terms of having higher heat dissipating characteristics than it of a case where a lead is disposed over a conventional heat dissipating device, but also in providing a semiconductor power module with improved reliability, productivity, and consistency because an inspection process for the bonded state of a heat dissipating plate is not needed.
The range of use of a DBC ceramic substrate has gradually expanded to use to as a semiconductor power module for vehicles due to the increase in use of such vehicles.
The DBC ceramic substrate comprises a ceramic base and a copper film and is manufactured by interfacial bonding force through a sintering process at high temperature.
As one example, a DBC ceramic substrate is manufactured by sintering a copper film of formed an alumina (Al2O3) ceramic base and a CuO oxide film thereon at 1000° C. to 1100° C. and forming an interfacial bonding between the alumina (Al2O3) ceramic base and the CuO oxide film.
For another example, a DBC ceramic substrate is manufactured by forming an Al2O3 layer on a surface of an AlN ceramic base through oxidation at high temperature, laminating a copper film on the surface of the AlN ceramic base copper film and sintering at 1000° C. to 1100° C., and then an interfacial bonding between the alumina (Al2O3) ceramic substrate and the CuO oxide film is formed.
When manufacturing a conventional DBC ceramic substrate, a sintering process at high temperature is needed for an interfacial bonding between the ceramic base and the copper film and also maintaining a reductive atmosphere is needed to prevent oxidation of Cu when sintering at high temperature.
That is, since sintering equipment capable of forming a reductive atmosphere is needed for manufacturing the conventional DBC ceramic substrate, cost for preparing sintering equipment thereby requiring is high.
In addition, since the conventional DBC ceramic substrate is manufactured by sintering at 1000° C. to 1100° C. and forming the interfacial bonding between the ceramic base and the copper film, it costs a lot to heat to a high temperature for sintering and takes a long time to manufacture, thereby productivity becomes low.
In addition, manufacture of the conventional DBC ceramic base is complicated since the CuO oxide film is formed on the copper film or the Al2O3 layer is formed on the surface of the AlN ceramic base and then sintered for the interfacial bonding.
Additionally, the conventional DBC ceramic substrate has problems with malfunction during use due to an adhesion problem between the copper film and the ceramic base thereby lowering operation reliability, particularly, when used as a semiconductor power module wherein if thermal shock occurs due to heat generation and cooling, the adhesion problem between the copper film and the ceramic base may be exacerbated.